Stratified Sampling Design Research Articles

Conventional Cigarette and E-Cigarette Smoking among School Personnel in Shanghai, China: Prevalence and Determinants.

Smoking cigarettes and e-cigarettes is widely popular among Chinese students. Considering that school personnel are considered role models in the student community, we investigated the prevalence and determinants of such behavior among high school personnel in China so as to provide references for future related intervention measures. We used a stratified cluster sampling design on a total number of 3311 school employees recruited from 33 representative schools. Complex sampling analysis and logistic regressions were used for univariate and multivariate analyses. Among 3194 participants that met the study criteria, 7.4% were cigarette users, and 3.6% e-cigarette consumers. For conventional cigarette smokers, certain characteristics, such as being older and male, attaining less education, and having been exposed to secondhand smoke, were associated with heavier smoking. Nevertheless, e-cigarette users were predominantly male and of younger age. Those who understood the hazards of conventional cigarette smoking had less inclination to smoke but were at a higher risk of e-cigarette use. Our analysis suggests that it is necessary to target different populations for monitoring and controlling conventional cigarette smoking and e-cigarette use respectively among school personnel. In addition, China is in need of more relevant and strict anti-smoking regulations.

Occurrence patterns of African manatees, conflicts with humans, and local perception in the Southern Korup Area, Cameroon

Abstract The African manatee has been poorly studied throughout its range and is heavily hunted. This study aimed at discerning patterns in manatee sightings and emerging conflicts with humans, as well as the local perception of manatees, outside the southern periphery of Korup National Park, Cameroon. The study investigated whether patterns in manatee sightings and manatee‐related conflicts differ between aquatic systems in southern Korup, and which demographic variables determine perceptions of the manatee in the study area. For this purpose, the study used a three‐stage stratified random sampling design with a structured questionnaire to survey 101 local fishers. The reported patterns of manatee sightings and manatee‐related conflicts were as follows: in the Nyangorobe River during the wet season only, where crop raiding and net destruction by manatees were reported; in the Ndian River and the mangrove estuary only during the dry season, where fish theft and net damage were reported; and in the Moko River during both seasons, where crop raiding, fish theft, and net destruction were reported. Reducing these conflicts is likely to increase local support for the conservation of manatees, because fishermen kill them in response to net destruction and fish loss. Most reported sightings were at waterway intersections and river bends, suggesting that waterway connectivity is important to manatees for dispersal, foraging, and escape from danger. The log‐odds probability of negative perception decreased significantly with awareness of manatee protected status but increased with age and primary or higher education level. These findings have implications for community outreach focused on raising awareness of the importance of manatee conservation by schoolchildren and the public.

Patterns of antenatal care services utilization in rural Amroha, Uttar Pradesh: a community based cross sectional study

Background: Antenatal care (ANC) services are considered to be the crucial element in the primary health care delivery system of a country. World Health Organization (WHO) estimates suggested that almost all of the maternal deaths (99%) and child deaths (98%) occurred in developing countries. These maternal deaths could have been prevented if the pregnant women or adolescent girls had been able to access quality antenatal care. The objectives of the present study were conducted in rural parts of district Amroha, Uttar Pradesh for assessing the patterns of utilization of the ANC services and to ascertain the factors influencing utilization of ANC services.Methods: The present study was a cross sectional in nature. Recently delivered women were selected as study subject. A multi-stage stratified sampling design with random approaches had been used. Total 360 subjects included in the study.Results: Respondents age, education, occupation, socio economic status, family type and family size were the factors that influenced the utilization of the ANC services. With 100% ANC registration, sub centre was the most preferred place for registration. 76.9% of woman received more than 3 ANC visits. 315 (87.5%) and (71.9%) respondents received 2 doses to TT vaccine and more than 100 IFA tablets respectively.Conclusions: Utilization of ANC services are on rise in rural parts of Amroha, Uttar Pradesh. Still significant proportions of women are doesn’t return to health facility after the ANC registration. Intensification of efforts is needed to cater this left out group through improving community awareness and motivation.

Population and Distribution of Swainson’s Hawks (Buteo swainsoni) in California’s Great Valley: A Framework for Long-Term Monitoring

The California Fish and Game Commission listed the Swainson's Hawk (Buteo swainsoni) as a state threatened species in 1983 in response to population reductions and habitat loss across the state. Human population increases, urbanization, and shifts in agricultural land use have the potential to affect California's Swainson's Hawk population. In 2005 and 2006, we conducted surveys to estimate the abundance and density of Swainson's Hawk breeding pairs in California's Great (Central) Valley, using a random sampling design stratified across dense, medium, and sparse nesting density strata. The sampling units comprised 2.59-km2 (1-mile2) US Public Land Survey System Sections, and the 2-yr survey covered an aggregate total of 682 sampling units (268 in 2005, 414 in 2006). Separate surveyors conducted independent surveys of 29 sampling units in 2006; based on these data, the estimated probability of detecting a single pair (if present) following the multiple-visits protocol was 0.81 (95% CI: 0.58–0.93). After applying this detection-probability correction and using generalized linear modeling of habitat associations to extrapolate density estimates throughout the study area, we estimated that the Great Valley supported 3218 (95% CI: 2271–4165) breeding pairs of Swainson's Hawks in 2005–2006. Our modeling of habitat associations showed crop diversity, alfalfa, and native vegetation as positively associated with the density of Swainson's Hawk breeding pairs, and orchards/vineyards negatively associated. Counts of breeding pairs were also highest in the middle latitudes of the Great Valley, which spans approximately 660 km from north to south. The predictive density model results had some areas of disagreement with the density strata used as basis for the stratified sampling design. To monitor the population status of this species throughout California, we recommend that our 2-yr sampling approach be expanded throughout the state and repeated every 5–10 yr. We also suggest this approach be used to monitor other special status raptor species to track population trend and distributional changes over time.

Spatially modelling the risk areas of chronic exposure to hydrothermal volcanic emissions using lichens

Human populations living in volcanically active areas are chronically exposed to volcanogenic air pollution, potentially contributing to long-term adverse health effects. However, mapping chronic exposure is difficult due to low spatial resolution of monitoring data on air pollutants and the need for time integration. To overcome these problems, lichens were tested as ecological indicators of hydrothermal volcanic air pollution, considering their bioaccumulation capacity over time, by transplanting them from a reference area to several sites (n = 39) in a volcanic area. The test was developed at Furnas volcano (Azores, Portugal). A stratified sampling design was followed using previous measurements of soil CO2 flux at ground level and the distance to the main fumarolic fields. After 6 months of exposure, lichen transplants were analyzed for S isotopic ratio (δ34S), which strongly related with the distance to fumarolic fields on a logarithmic regression, serving as an appropriate hydrothermal exposure biomarker. Considering kriging interpolated δ34S values as tracer of airborne hydrothermal emissions and habitational areas as proxy of ongoing human presence, a map was built relating both information per area unit to spatially model risk areas. It was estimated that 26% of habitational areas in the study area stand at high or very high risk of outdoors chronic exposure to airborne hydrothermal emissions. This methodologic approach to produce chronic exposure risk maps is applicable to other volcanically active and inhabited areas of the world, with time-integration and high spatial resolution, contributing in this way for spatially focusing future human health assessments.

Dynamic and integrative approaches to understanding pathogen spillover.

Dynamic and integrative approaches to understanding pathogen spillover.

Relationship of forest biomass carbon with biophysical parameters in north Kashmir region of Himalayas

Biophysical parameters affecting biomass carbon have been emphasized in the Paris Agreement for realizing climatic benefits from mitigation projects. The present study was conducted to assess the relation of biophysical parameters with forest biomass carbon in north Kashmir region of Himalayas. The relation of biomass carbon was assessed with (1) species type or strata including Cedrus deodara, mixed I (Cedrus deodara-Pinus wallichiana), mixed II (Abies pindrow-Picea smithiana) and Pinus wallichiana, (2) altitude (1292-2911m amsl), (3) crown density, (4) aspect, (5) tree count or density and (6) location. Using a stratified sampling design, a total of 188 quadrats of 0.1ha were laid across the entire region representing different biophysical parameters. Field observation including diameter at breast height and height were recorded and sample biomass (tha-1) was estimated using volumetric equations. The observed relation of aboveground biomass carbon with species revealed a trend of mixed II ˃ Cedrus deodara ˃ mixed I ˃ Pinus wallichiana. A positive but weak correlation (R2 = 0.02) was found between aboveground biomass carbon and altitude. A reasonably good correlation (R2 = 0.40) was observed to exist between aboveground biomass carbon and crown density. The highest value of average biomass carbon (72.63tha-1) was recorded for the north-eastern aspect whereas the lowest value (44.60tha-1) was recorded for the eastern aspect. The aboveground biomass carbon and tree count was found positively correlated (+ 0.475, R2 = 0.48). Forest biomass carbon fluctuates within the same geographical region with a variety of biophysical factors. The growth rate of species, photosynthetic ability under different crown densities and climatic conditions could address the reasons for this variability. Biophysical relations of forest biomass carbon can be viewed as an important input for guidelines and policy matters on climate change.

Oral health status and caries trend among 12-year old Palestine refugee students: results from the UNRWA\u2019s oral health surveys 2011 and 2016

BackgroundIn 2016 the United Nation Relief and Work Agency for Palestine refugees in the Near East (UNRWA) commissioned a survey on oral health among 12-year-old students at UNRWA schools in five fields of operation (Jordan, Lebanon, Syria, Gaza Strip and West Bank), following World Health Organization guidelines. The survey aimed to determine the prevalence of dental caries and periodontal diseases among Palestine students attending UNRWA schools and how this has changed over time.MethodsA two-stage stratified cluster sample design was used. For each Field of operation, the sample size was calculated based on 95% confidence level, 80% power and margin of error of 4%. Clinical examination was carried out by trained Field Oral Health services Officers (FOHSOs) from the 5 fields. Teeth presence and condition, gingival bleeding and calculus and the presence of dental sealants in occlusal surfaces of permanent molars were recorded. Behavior information of students/parents were collected using a questionnaire that was self-completed by the child/parent under supervision. Results were compared with those from a previous survey carried out in 2011 with the same methodology.ResultsIn the two surveys the distributions of students who had caries experience in their permanent teeth were similar (73.1% in 2011 vs 72.8% in 2016, p = 0.83). In 2016 a significant increase of missing teeth (p < 0.01) and sealants (p < 0.01) was observed. Both surveys have identified behavioral determinants for dental caries, particularly dietary habits such as soft drinks consumption. Gingival health also showed statistical differences among the fields.ConclusionsThe prevalence of caries experience was very high in all fields and, with regard to main oral health indices, no trend of improvement was observed through 2011 and 2016. Surveys’ results advocates the need of a large-scale integrated preventive approach toward oral health and the emerging growth of Noncommunicable Diseases (NCDs), in line with the WHO recommendations.

Finite mixture of regression models for a stratified sample

ABSTRACTDespite the popularity and importance, there is limited work on modelling data which come from complex survey design using finite mixture models. In this work, we explored the use of finite mixture regression models when the samples were drawn using a complex survey design. In particular, we considered modelling data collected based on stratified sampling design. We developed a new design-based inference where we integrated sampling weights in the complete-data log-likelihood function. The expectation–maximisation algorithm was developed accordingly. A simulation study was conducted to compare the new methodology with the usual finite mixture of a regression model. The comparison was done using bias-variance components of mean square error. Additionally, a simulation study was conducted to assess the ability of the Bayesian information criterion to select the optimal number of components under the proposed modelling approach. The methodology was implemented on real data with good results.

Coverage and factors associated with full immunisation among children aged 12–59 months in Bangladesh: insights from the nationwide cross-sectional demographic and health survey

ObjectiveTo estimate the coverage and factors associated with full immunisation coverage among children aged 12–59 months in Bangladesh.Study designThe study is cross sectional in design. Secondary dataset from Bangladesh Demographic...

Influence of Promotional Marketing Practices on Performance of Domestic Tourism in Kenya: A Case of County Government of Nakuru

Abstract&#x0D; International tourism in Kenya has become increasingly vulnerable to international shocks, giving rise to interest in domestic tourism as an attempt to sustain the tourism market. The County Government of Nakuru has accordingly put in place various measures to market the sector domestically. This study aimed to assess the effect of these measures on performance of domestic tourism of the County Government of Nakuru, Kenya. The basic communication theory as developed by Schramm was used to guide the study. The study employed the proportionate stratified sampling design with three strata namely tourist hotels, tourist attractions and the Ministry of Trade, Industrialisation, Tourism and Wildlife Management at the County Government of Nakuru. Simple random sampling by raffle was further used inside each stratum in order to give each subject an equal chance of being selected. Data was collected through structured questionnaires comprising of closed-ended questions. Data was analysed using SPSS and Excel spreadsheets. Findings indicated a strong relationship of all the independent variables to the dependent variable This led to the conclusion that promotional marketing activities do influence performance of domestic tourism. Consequently, it was recommended that adequate resources should be allocated for promotional activities, especially financial resources and human resources. For better effectiveness, it was recommended that the promotional activities should be integrated rather than applied separately, and that all stakeholders should be engaged.

Methodology and Representativeness of the Adolescent Health Survey 2017 in Malaysia

Health risk behaviors and mental health problems are associated with morbidity and premature mortality among adolescents. Understanding the magnitude of the problem may improve adolescent health status. The Adolescent Health Survey was conducted to collect data on health risk behaviors among Malaysian school-going adolescents using self-administered questionnaires. A 2-stage stratified cluster sampling design was used and samplings weights were calculated to ensure representativeness to the general population. A total of 27 497 out of 30 823 school-going adolescents completed the questionnaires, yielded an 89.2% overall response rate. The methodology was robust to ensure valid estimation on the prevalence of health problems among Malaysian school-going adolescents.

The occurrence and density of three sympatric corvids in a Mediterranean agroecosystem explained by land use

Agroecosystems harbour common species besides farmland birds, which are often understudied because they are not appealing to researchers. However, common species are fundamental to the structure of most ecosystems, so if the preservation of an overall pattern of species richness is a valid conservation goal, we need to improve our knowledge of them. Corvids are some of the most common species in agroecosystems, and are considered in some countries to be farmland birds. The aims of this research were to estimate the densities, assess the habitat selection, and measure the niche overlap of three corvid species, the Eurasian Jay (Garrulus glandarius), the Eurasian Magpie (Pica pica), and the Hooded Crow (Corvus cornix), in a Mediterranean agroecosystem. To collect data, a stratified random sampling design was used; 264 linear transects were walked during the winter, and 301 point counts carried out during the breeding season. The densities of the three species were estimated through the distance sampling method, whereas the evaluation of habitat selection was performed by a binary logistic regression following an information-theoretic approach. To define the niche overlap of the three species both during the winter and the breeding season, the Hurlbert index of niche overlap was used. The results showed that, in the Mediterranean agroecosystem, the most abundant species is the Eurasian Magpie, which occurs in built-up areas at lower densities than in the countryside. The Eurasian Jay typically selects woodland during the breeding season, but can shift its niche to agricultural land. The estimated density for Hooded Crows was higher here than those recorded in other climatic regions, even though the scarce presence of open water has been described as a limiting factor for this species. Finally, our results showed that there is some overlap in niche between these three species. In particular, the niche of the Eurasian Jay and Hooded Crow overlap both during the winter and during the breeding season, whereas the Eurasian Jay niche overlaps with that of the Eurasian Magpie in the winter, which in turn overlaps with that of the Hooded Crow during the breeding season.

Plant Community Composition and Biodiversity Patterns in Urban Parks of Portland, Oregon

Urban parks are biodiversity hotspots and are integral components of green infrastructure in urban areas. A variety of land use practices and environmental factors affect urban park biodiversity and vegetation structure, composition, and ecological function, but few studies have compared plant taxonomic composition, structural complexity, and species traits across different types of urban green spaces. The purpose of this study was to better understand the relationships between plant community composition, structural patterns, and environmental and species traits by using a standardized data collection method across different types of urban parks in Portland, Oregon. We examined the potential ways that different types of urban parks preserve native species and/or harbor non-native and invasive species. We used a stratified random sampling design to select 15 parks of different types based on use: 1) recreational-active use parks, 2) natural-passive use parks, and 3) multi-use parks. We found a total of 178 plant species belonging to 141 genera and 65 families. Multivariate analyses, including ordination with non-metric multidimensional scaling and cluster analysis were used to explore vegetation composition data and associations of different species assemblages with environmental variables. One-way analysis of variance was used to test hypotheses about variables associated with diversity. Statistically-significant differences in species richness and biodiversity indices were found between different park types. More native species were found in natural-passive use parks than other park types, more non-native species are found in multi-use parks than the other park types, and more invasive species were found in natural passive-use parks than in recreational-active use parks. Attributes such as natural-passive use park type, wetland habitat, steep slopes, native species origin, non-native species origin, and vine and tree plant forms were those most strongly correlated with the non-metric multidimensional scaling ordination, indicating that these attributes exert the strongest influence on species abundance and distribution with Portland’s urban parks. The findings of this study can assist park managers in their aims to promote native species cover, reduce invasive species presence, or achieve additional management goals for urban parks.

Food Allergy Management in Elementary, Middle and High Schools of Korea (P04-058-19)

ObjectivesThe prevalence of food allergies has been increasing in Korean schools. The need for food allergy management in school meals has become important. The purpose of this study was to investigate the level of knowledge on food allergies and the actual condition of school food management by nutrition teachers, health teachers, and homeroom teachers. MethodsThis survey was conducted in cooperation with the Ministry of Education September 2015. From 17 cities and provinces, a total of 1000 elementary, middle, and high schools were selected by a 2-stage stratified random sampling design. Nutrition teachers, health teachers and homeroom teachers were surveyed using a questionnaire on the perception and management status of food allergy. ResultsAccording to the results, 2.5% of nutrition teachers, 2.9% of health teachers, and 47.3% of homeroom teachers answered that they do not know about anaphylaxis, which is a severe food allergy symptom. Of the total nutrition teachers, 96.6% knew the causal foods of anaphylaxis, and 79.2% answered that students with food allergy tried not to be exposed to the causal food during lunch time or class. However, 44.1% of the nutrition teachers, 64.8% of the health teachers, and 79.2% of the homeroom teachers answered that they have never received training or education about food allergy. In case of a food allergy accident occurrence, 66.9% of the respondents replied that ‘would not administer emergency treatment’. The reasons for this, 85.8% of the respondents said ‘If the health teacher is in charge of emergency management, there are legal problems that conflict with other medical laws’, and 79.3% responded that ‘there is no legal protection for a manager against food allergy accidents’, and 14.6% answered ‘do not know how to manage food allergy’ ConclusionsAlthough most nutrition and health teachers except homeroom teachers are aware of the risk of food allergy and anaphylactic reactions, there is insufficient management system and legal guarantee in case of emergency and systematic education on food allergy management methods. Therefore, there are necessary to develop guidelines for food allergy management to cope effectively and systemically for the emergency situations, and to be continuous educations of food allergy for teachers Funding SourcesNo funding.

Diversity and floristic composition of rural and sub-urban home garden in Wadera district of Oromia region, Ethiopia

This study was conducted in Wadera district of Oromia region in Ethiopia, with the objective of quantifying the diversity and floristic composition of home garden agroforestry systems. A stratified random sampling design was used to select 132 sample home gardens and a detailed inspection was conducted on diversity and floristic composition of the plant species using the Shannon-Wiener diversity index and Pielou’s Evenness index. A total of 65 cultivated plant species belonging to 36 families were recorded with an average of 28 plant species per individual’s home garden. Rutaceae was the dominant family with 6 species followed by Lamiaceae and Solanaceae. Shannon’s diversity indexes of 1.63 to 2.06 were recorded at the village level with an overall mean diversity index (H’) of 1.85 and evenness index (E) of 0.58. The findings from this study may help government and other stakeholders in providing baseline information, supported with scientific evidence, which further can contribute to policy and decision making process. Key words: Agroforestry, home garden, diversity, floristic composition, Guji zone.

Optimum allocation in multivariate stratified sampling design in the presence of nonresponse with Gamma cost function

ABSTRACTIn multivariate stratified sample survey with L strata, let p-characteristics are defined on each unit of the population. To estimate the unknown p-population means of each characteristic, a random sample is taken out from the population. In multivariate stratified sample survey, the optimum allocation of any characteristic may not be optimum for others. Thus the problem arises to find out an allocation which may be optimum for all characteristics in some sense. Therefore a compromise criterion is needed to workout such allocation. In this paper, the procedure of estimation of p-population means is discussed in the presence of nonresponse when the use of linear cost function is not advisable. A solution procedure is suggested by using lexicographic goal programming problem. The numerical illustrations are given for its practical utility.

Adoption Level of Agroforestry Practices in Katsina State, Nigeria

Unsustainable forest land use practices have resulted in land degradation in Nigeria leading to low crop yield. Agroforestry is a viable option for reversing dwindling crop yields through proper soil management practices. There is notably no sufficient published information on agroforestry practices (AP) in Katsina State. The aim of this study was to assess AP for sustainable land use in the study area. Multistage stratified sampling design was used to select respondents from the study. Three Local Government Areas (LGAs) were randomly selected from each of the agro-ecological zones (Sahel, Sudan and Guinea) of Katsina State. Within each of the selected LGAs, one community was randomly selected and forty respondents were randomly sampled from each community. Using structured questionnaire, information was sought on socio-economic and AP. Data were analysed using descriptive statistics. Based on the results, multipurpose trees on farmland (79%), windbreaks (50%), woodlots (49.7%), improved fallow in shifting cultivation (32%) and home gardens (24.7%) were the common AP in the study area. Benefits of AP in the area included preservation of the environment (98.5%), provision of fruits and leaves (98%), and improvement of soil fertility (98%), erosion control (98%) and improvement of farmers’ income (96%). Agroforestry practices enrich the soil with important nutrients and prevent soil erosion. The adoption of multipurpose trees on farmland in the study area will help in preventing environmental degradation, desertification and enhance food crop production.

Colonial history impacts urban tree species distribution in a tropical city

Urban forests associated with green infrastructure for sustainable outcomes are particularly critical in the Global South, where some of the world’s fastest-growing cities are located. However, compared to temperate cities, the drivers of urban tree species distribution in tropical cities remain understudied. In this study, we quantify the spatial distribution and abundance of urban forests in the tropical city of Georgetown, Guyana. British colonialism has shaped this city, including forced movement of peoples under slavery from Africa and indentured servants from the Indian Subcontinent. We studied how this multicultural context has influenced tree species distributions in the capital city of the only Anglophone country in South America. We quantified the abundance of tree species using a stratified sampling design to distribute transects across fifteen neighborhoods that vary in distance to the colonial center of the city and ethnic composition. We recorded a total of 57 unique species, the majority of which (73%) were cultivated for their edible fruits. We identify tree species that likely represent Guyana’s unique multicultural heritage by comparing our species list to flora in nine cities in neighboring countries (Venezuela and Brazil) with different colonial histories. This international comparison identified a set of tree species that occurred only in Guyana. Relationships between ethnic composition and colonial history and tree species distribution were weak at the neighborhood scale, where proportion of East Indian residents had little explanatory power and distance to colonial center was correlated with abundance of only some species groups. This apparent discrepancy between neighborhood and national scales may relate to the establishment of Guyanese food as a unifying national identifier across ethnicities. The prominence of edible fruit trees in our study suggests a set of species that could be incorporated into urban planning to strengthen biocultural linkages, foster cultural integration, and promote food security.

Some calibration estimators for finite population mean in two-stage stratified random sampling

In the present article, an effort has been made to develop calibration estimators of the population mean under two-stage stratified random sampling design when auxiliary information is available at primary stage unit (psu) level. The properties of the developed estimators are derived in-terms of design based approximate variance and approximate consistent design based estimator of the variance. Some simulation studies have been conducted to investigate the relative performance of calibration estimator over the usual estimator of the population mean without using auxiliary information in two-stage stratified random sampling. Proposed calibration estimators have outperformed the usual estimator without using auxiliary information.